1. (Field of the Invention)
The present invention relates to a method for lining a branch pipe of an underground main pipe by applying a lining material on the inner wall of the branch pipe.
2. (Description of the Prior Art)
When an underground pipe, such as pipelines and passageways, becomes defective or too old to perform properly, the pipe is repaired and rehabilitated without digging the earth to expose the pipe and disassembling the sections of the pipe. This non-digging method of repairing an underground pipe has been known and practiced commonly in the field of civil engineering. Typically, the method is disclosed by Japanese Provisional Patent Publication (Kokai) No. 60-242038.
According to this publication, this method of pipe repair comprises inserting a sufficiently long tubular flexible liner bag into the pipe to be repaired by means of a pressurized fluid, like air and water. The tubular liner bag is made of a flexible resin-absorbent material impregnated with a thermosetting resin, and has the outer surface covered with an impermeable plastic film.
More particularly, according to the publication, the tubular flexible liner bag is closed at one end and open at the other; the tubular flexible liner bag is first flattened, then, the closed end of the tubular liner bag is tied to a control rope; the open end of the tubular liner bag is made to gape wide and hooked (anchored) at the end of the defective or old pipe in a manner such that the wide-opened end of the liner completely and fixedly covers and closes the pipe end; a portion of the liner is pushed into the pipe; then, the pressurized fluid is applied to the said portion of the tubular liner such that the fluid urges the tubular liner to enter the pipe. Since one end of the tubular liner is hooked at the end of the pipe, it remains there while the rest of the flexible liner bag is turned inside out as it proceeds deeper in the pipe. (Hereinafter, this manner of insertion shall be called "everting".) When the entire length of the tubular liner bag is everted (i.e., turned inside out) into the pipe, the control rope holds the closed end of the tubular liner bag to thereby control the length of the tubular liner in the pipe. Then, the everted tubular liner is pressed against the inner wall of the pipe by the said pressurized fluid or by an inflatable pressure bag, and the tubular flexible liner is hardened as the thermosetting resin impregnated in the liner is heated, which is effected by heating the fluid filling the tubular liner bag by means of a hot steam, etc. It is thus possible to line the inside wall of the defective or old pipe with a rigid liner without digging the ground and disassembling the pipe sections.
This method in principle applicable to a pipe branching out from a main pipe as well, and an example of how it is conducted will be described next with reference to FIG. 8.
FIG. 8 is a vertical sectional view of a sewerage site, showing the conventional method of lining a pipe 102 branching out from a main pipe 101. The reference numeral 116 designates a rigid everter introduced and positioned in the main pipe 101 in a manner such that the eversion end of it peeps up the branch pipe 102, and it is closed at the other end, the right end as viewed in FIG. 8, and contains in it an inflatable pressure bag 140 and a tubular branch pipe liner 104 trimmed to a length corresponding to that of the branch pipe 102. While packed in the everter 116, the liner 104 is within the pressure bag 140, which is for pressing the liner 104 against the inner wall of the branch pipe, the liner 104 comes outside the pressure bag 140 when everted out from the everter 116, as shown in FIG. 8. The branch pipe liner 104 must be detached from the everter 116 so that it is necessary to anchor the inflatable pressure bag 140 to the open end of the everter 116.
When pressurized air or liquid is supplied to the everter 116, the pressure bag 140 together with the branch pipe liner 104 is everted into the branch pipe 102, and while keeping the pressure bag 140 inflated, the tubular branch pipe liner 104 is heated to cure the hardenable liquid resin impregnated in it, whereupon the liner 104 becomes rigid. Then, the pressure bag 140 is removed from the branch pipe 102 (branch pipe liner 104) to leave the branch pipe 102 neatly lined with the hardened branch pipe liner 104 to complete the repair.
However, in the above method, the pressure bag 140 had to be replaced with one of a different length each time the branch pipe of a different length was repaired, and this necessitated the tiresome labor of changing the pressure bags 140.
Thus, an improved branch pipe lining method was proposed which will next be explained with reference to FIGS. 9 through 11.
FIGS. 9 through 11 are cross-sectional views to show the conventional branch pipe lining method in order of the operation. According to this method, an everter 216 and a branch pipe liner bag 204 are hermetically connected to each other via a fluid pressure sealing nozzle 207, as shown in FIG. 9, and the hermetical connection of the fluid pressure sealing nozzle 207 with the collar 204A of the branch pipe liner bag 204 is attained by means of any of the mechanical seal assemblies (a) through (d) illustrated in FIG. 12.
We will briefly explain each of the mechanical seal assemblies (a) through (d) with reference to FIG. 12.
The mechanical seal assembly (a) in FIG. 12 has a tapered railing 207a extending from the fluid pressure sealing nozzle 207, and by virtue of this railing 207a the fluid pressure sealing nozzle 207 is connected hermetically to the branch pipe liner bag 204.
The mechanical seal assembly (b) of FIG. 12 employs an O ring 230 buried in the flange of the fluid pressure sealing nozzle 207, while the mechanical seal assembly (c) of FIG. 12 employs a valve 231 provided on the fluid pressure sealing nozzle 207 to attain hermetic sealing at the joint of the fluid pressure sealing nozzle 207 with the branch pipe liner bag 204.
In the case of the mechanical seal assembly (d) of FIG. 12, the collar 204A of the branch pipe liner bag 204 is inlaid with magnet plates 232, and these are attracted by the magnet blocks 233 provided on the lower face of the flange portion of the fluid pressure sealing nozzle 207 whereby the collar 204A is firmly held on the fluid pressure sealing nozzle 207 to hermetically close the space between the nozzle 207 and the branch pipe liner 204.
Thus, as shown in FIG. 9, the collar 204A of the branch pipe liner bag 204 packed in the everter 216 is placed on the fluid pressure sealing nozzle 207, and by employing an on-the-sleigh robot 203 the fluid pressure sealing nozzle 207 is pushed upward to thereby press the collar 204A of the branch pipe liner bag 204 against the inner wall of the main pipe 201 so that the collar 204A is anchored at the entrance of the branch pipe 202. Then, a compressor 219 is started to supply compressed air to the everter 216 by way of an air hose 218, whereupon the branch pipe liner bag 204 is urged by the pressure of the compressed air to evert into the branch pipe 202, running upward from the main pipe 201 to the surface of the ground.
When the entire length of the branch pipe liner bag 204 is everted and penetrates the branch pipe 202, the closed end of the branch pipe liner bag 204 is cut open and a pressure cup 250, as shown in FIG. 10, is connected to the upper end of the branch pipe liner 204 to close the opening. A hot water hose 221 and an air hose 222 are provided to penetrate this cup 250. Hot water and compressed air are supplied into the branch pipe liner 204 by way of a hot water hose 221 and an air hose 222, respectively.
Then, the branch pipe liner bag 204 is inflated and pressed against the inner wall of the branch pipe 202 by the pressure of the compressed air, as shown; and at the same time, the thermosetting liquid resin impregnated in the branch pipe liner bag is heated by the hot water and as it cures the branch pipe liner bag becomes hard and rigid.
That part of the branch pipe liner 204 which extends outside the branch pipe 202 is cut off, and consequently, the inner wall of the branch pipe 202 is closely lined with the branch pipe liner 204.
After the branch pipe liner 204 is hardened, the on-the-sleigh robot 203 is driven to lower its piston rod and is pulled back by a pull rope 208, whereupon the fluid pressure sealing nozzle 207 is easily detached off the collar 204A of the branch pipe liner 204, as shown in FIG. 11.
As the on-the-sleigh robot 203 is drawn back by the pull rope 208 rghtward, as seen in FIG. 11, the fluid pressure sealing nozzle 207 and the everter 216 are all together pulled in the same direction and removed from the main pipe 101. Thus, the hardened branch pipe liner 204 alone is left in the branch pipe 202, and the lining operation of the branch pipe 202 is completed.
According to the invention, therefore, the pressure bag 140 of FIG. 8 can be dispensed with, and thus it is not necessary to replace the pressure bag 140 each time a branch pipe of different length is lined.
(Problems the Invention seeks to solve)
However, although high sealing effect is required at the juncture between the branch pipe liner bag 204 and the fluid pressure sealing nozzle 207, none of the mechanical seal assemblies (a) through (d) of FIG. 12 employed in the conventional branch pipe lining method has proved satisfactory.
Therefore, it is an object of the invention to provide a branch pipe lining method in which it is possible to effect a highly hermetic junction between the branch pipe liner bag and the fluid pressure sealing nozzle by means of a simple construction, and it is also possible to conduct a highly smooth eversion of the branch pipe liner bag into the branch pipe.
Generally, an access space to a branch pipe is about 400 mm in diameter, and is not as wide as the main pipe manhole which usually has a diameter of 900 mm, so that it was impossible for a man to do manual operations inside the access space, and it was necessary to evert the branch pipe liner bag as high as the position where a man could reach the bag by hand. For this reason, as shown in FIG. 10, the branch pipe liner bag 204 was everted until it rose up to the surface of the ground, and a pressure cup 250 was connected to the upper end of the branch pipe liner 204, and a hot water hose 221 and an air hose 222 were provided to penetrate this pressure cup 250. This necessitated troublesome operations, and inasmuch as that part of the branch pipe liner 204 which protrudes beyond the upper end of the branch pipe 202 was wasted, this procedure was not economical.
Therefore, it is another object of the invention to provide a branch pipe lining method which is improved such that the operation is much simpler and the wasted part of the branch pipe liner is substantially reduced, so that the operation is greatly economized.
(Means to solve the Problems)
In order to solve the above problems and others, there is proposed a method for lining a branch pipe of an underground main pipe comprising the steps of: (a) preparing a tubular liner bag made of a nonwoven fabric soaked with a hardenable liquid resin, one end of said tubular liner bag being closed; (b) turning outwardly the open end of said tubular liner bag to form a collar which is so curled as to have a curvature equal to that of the inner wall of the main pipe; (c) curing the liquid resin in said collar to thereby harden the collar; (d) embedding stopper tacks in said collar at appropriate locations, each of said stopper tacks having its bottom end exposed from the back face of said collar and connected with a string; (e) facing the back face of the collar of the branch pipe liner bag with the upper face of a flange of a fluid pressure sealing nozzle, which comprises a hollow cylindrical part, through which the liner bag is passed, the flange extending perpendicularly from the side of said cylindrical part, at least one endless sealant laid on the upper face of said flange, and a string pull means provided in said flange; (f) engaging said strings with said string pull means of the flange; (g) causing said string pull means to pull said strings so that the collar and the flange are moved toward each other until sufficient sealing effect is obtained at the juncture between the collar and the flange by means of the endless sealant; (h) packing that portion of said liner bag which is tailing out from the fluid pressure sealing nozzle in an everter, which is a tubular body with one end closed; (i) connecting the open end of said everter with the bottom end of the cylinder part of the fluid pressure sealing nozzle in a manner such a closed space is defined by the inner wall of the everter, the inner wall of said cylindrical part and the outer surface of the uneverted part of the liner bag; (j) positioning said fluid pressure sealing nozzle together with the everter at the opening of the branch pipe in the main pipe such that the collar is fitted on the inner wall of the main pipe around the opening of the branch pipe; (k) everting said branch pipe liner bag into the branch pipe from the fluid pressure sealing nozzle toward the surface of the ground by supplying pressurized fluid into said closed space from the closed end of the everter; (1) hardening said hardenable liquid resin impregnated in the branch pipe liner bag while keeping the liner bag inflated by means of the fluid pressure; (m) severing said strings and detaching the fluid pressure sealing nozzle from the collar of the branch pipe liner bag; and (n) cutting off that portion of said liner bag which protrudes outside the branch pipe.
In a preferable embodiment, the method is characterized in that at the step (d) above said string is each provided with a hook tied at the free end; and at the step (e) said string pull means comprises a plurality of internally threaded sleeves extending perpendicularly downward from the lower face of the flange, the sleeves being arranged at locations which coincide with said stopper tacks of said collar, each one of said sleeves containing a bolt screwed upwardly in it, each one of said screws having a freely rotatable catch means at its tail end; and at the step (f) said hooks are engaged with the respective catches of said bolts; and at the step (g) said bolts are turned in the direction to pull said strings into said sleeves so that the collar and the flange are moved toward each other.
In a more preferred embodiment of the invention, the method is characterized in that at the step (e) above said fluid pressure sealing nozzle further comprises an electric heater provided at each one of said threaded sleeves, and at the step (m) said strings are severed by being heated by said electric heaters.
In another embodiment of the invention, the method is characterized in that said hardenable liquid resin is a thermosetting resin and at the step (1) above said hardening is effected by supplying hot liquid through a pipe which is stabbed into the upper end portion of the everted branch pipe liner bag, and similarly said fluid pressure to keep the liner bag inflated is supplied through another pipe which is also stabbed into the upper end portion of the liner bag.
(Effects of the Invention)
According to the method of the present invention, the collar of the branch pipe liner bag is pressed on the endless sealant laid on the flange of the fluid pressure sealing nozzle as it is pulled by the strings, so that it is possible to effect a highly hermetic junction between the collar of the branch pipe liner bag and the flange of the fluid pressure sealing nozzle by means of the simple construction, and thus it is also possible to conduct a leakless eversion of the branch pipe liner bag into the branch pipe.
Also, after the branch pipe liner bag inserted into the branch pipe by eversion is hardened, one has only to server the strings by electric heaters, etc. in order to detach the fluid pressure sealing nozzle from the branch pipe liner bag, so that scarce labor is required at this time.
Furthermore, since lengthy pipes are stabbed into the upper end of the everted branch pipe liner bag in order to supply hot liquid and fluid pressure to effect hardening of the branch pipe liner bag while it is kept inflated, there is no need of everting the branch pipe liner bag as high as the position where a man could reach the bag by hand, nor is it necessary to attach a pressure cup at the upper end of the everted liner bag. Therefore, the operation is much simplified and the wasted part of the branch pipe liner is substantially reduced, and a economical operation can be achieved.
The above and other objects and features of the invention will appear more fully hereinafter in the following description given in connection with the accompanying drawings and the novelty thereof pointed out in the appended claims.